Known types of such devices comprise a great number of electrically, mechanically or electromagnetically operated contacts, for instance a great number of relays, an action control switch with a complicated contact arrangement. Such contacts not only have the disadvantage of often suffering from disturbances which are difficult to locate, but it is also difficult and expensive to survey the numerous mutual interdependence of the different circuits, parts and controls in such a manner as to prevent a faulty operation of the device. The possibility of a faulty service and the occurence of a faulty operation of the device should be avoided due to the strict regulations imposed by the regulatory Communications Agency.
It is the aim of the present invention to considerably decrease in the above named device the number of mechanical, electro-mechanical or electro-magnetic switch elements and to establish a practically unlimited number of circuit connections in order to prevent any faulty operation.